Coal water slurry dividing wall type heat compensation type gas comprehensive utilization system and coal water slurry dividing wall type heat compensation type gas comprehensive utilization method

Abstract

The invention discloses a coal water slurry dividing wall type heat compensation type gas comprehensive utilization system and method. The system comprises a mixer, a Roots blower, a material returning device, a dust remover, a heat storage oxidation device, a secondary air exhaust gas preheater, a primary air exhaust gas preheater and an induced draft fan which are connected in sequence. The secondary air exhaust gas preheater is connected with a secondary fan; the primary air exhaust gas preheater is connected with a primary fan; the heat storage oxidation device is connected with the waste heat boiler; the secondary air exhaust gas preheater is connected with the coal water slurry combustion device; by means of the coal mine gas extraction system, the situation that the working condition temperature of all points in the system is lost until the system is shut down due to unstable flow and concentration of coal mine gas extraction can be avoided, the coal mine gas extraction efficiency is improved, and the coal mine gas extraction efficiency is improved. Therefore, heat supply interruption to heat consumers is avoided, the heat interruption risk is reduced, and the operation cost and the safety risk of the device are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas recycling systems, and particularly relates to a water coal slurry indirect heat supplement type gas comprehensive utilization system; it also relates to a water coal slurry indirect heat supplement type gas comprehensive utilization method. Background Art

[0002] The main component of gas is methane, which is a strong greenhouse effect gas with a greenhouse effect 25 times that of carbon dioxide. At the same time, gas is also an important unconventional natural gas resource. Extracting and utilizing gas can not only reduce coal mine disasters but also reduce greenhouse gas emissions, achieving multiple benefits. Among the utilization methods of gas, low-concentration gas with a methane concentration of 8% - 30% is mainly used for power generation, while ultra-low-concentration coalbed methane with a concentration less than 8% is mixed with air exhaust gas (or air) to make the concentration of the mixed gas stable at 1.5% and then enter the regenerative oxidation device. Methane undergoes an oxidation reaction in the combustion chamber of the regenerative oxidation device to form high-temperature flue gas, which provides heat for coal mine heat users. The direct consequence of low gas utilization efficiency is a large amount of methane emissions and serious environmental pollution.

[0003] The regenerative oxidation device has a self-heat balance concentration, and the prerequisite for its normal operation is that the concentration of the gas mixture in the device is higher than its self-heat balance concentration. The flow rate and concentration of the gas extracted from coal mines are unstable, and sometimes there is even a long-term supply interruption, resulting in the temperature loss of the working conditions at each point inside the gas regenerative oxidation device during operation until it stops. Once the temperature in the combustion chamber drops below the ignition point of methane, the furnace needs to be restarted. On the one hand, the heat supply to heat users will stop after shutdown, and on the other hand, restarting the furnace will increase costs and safety risks.

[0004] In addition, the methane concentration of air exhaust gas is generally lower than 0.2%, which is lower than the self-heat balance concentration of the regenerative oxidation device. Therefore, if the concentration of the extracted gas is lower than the self-heat balance concentration or the supply is interrupted, the air exhaust gas cannot independently operate the regenerative oxidation device and can only be discharged, causing environmental pollution. Summary of the Invention

[0005] The purpose of the present invention is to provide a water coal slurry indirect heat supplement type gas comprehensive utilization system, which solves the problems of temperature loss and even shutdown of the regenerative oxidation device during operation and termination of heat supply caused by a serious reduction or even interruption of the concentration of the extracted gas.

[0006] The technical solution adopted by the present invention is as follows: a water slurry indirect heat-supplemented type gas comprehensive utilization system, which includes a mixer, a Roots blower, a return feeder, a dust collector, a regenerative oxidation device, a secondary air exhaust gas preheater, a primary air exhaust gas preheater, and an induced draft fan connected in sequence; the secondary air exhaust gas preheater is connected to a secondary blower; the primary air exhaust gas preheater is connected to a primary blower; the regenerative oxidation device is connected to a waste heat boiler; the secondary air exhaust gas preheater is connected to a water slurry combustion device; the primary air exhaust gas preheater is connected to the ignition air duct of the water slurry combustion device; it also includes a control system, and the control system is used to control each valve body on the connecting pipeline to achieve flow regulation.

[0007] The characteristics of the present invention also lie in that A water slurry storage funnel is connected to the water slurry combustion device. The regenerative oxidation device includes a combustion chamber and two groups of regenerators arranged at intervals, and a finned tube heat exchange coil is arranged in the combustion chamber.

[0008] The outlets of the secondary blower and the primary blower are respectively connected to the two cold fluid inlets of the low-temperature energy-saving device through regulating valves V5 and V6. The inlets of the cold fluids of the secondary air exhaust gas preheater and the primary air exhaust gas preheater are respectively connected to the two cold fluid outlets of the low-temperature energy-saving device; the outlets of the cold fluids of the secondary air exhaust gas preheater and the primary air exhaust gas preheater are respectively connected to the furnace and the ignition air duct of the water slurry combustion device.

[0009] The outlet of the mixer is connected to the regenerator of the regenerative oxidation device through a cut-off valve group; the high-temperature flue gas outlet at the top of the regenerative oxidation device is connected to the heat source inlet of the waste heat boiler through a regulating valve V4. The heat source outlet of the waste heat boiler is connected to the hot fluid inlet of the low-temperature energy-saving device, and the hot fluid outlet of the low-temperature energy-saving device is connected to the chimney.

[0010] The hot fluid inlet of the finned tube heat exchange coil is connected to the gas outlet end of the dust collector, and the hot fluid outlet is connected to the hot fluid inlet of the secondary air exhaust gas preheater; the hot fluid outlet of the secondary air exhaust gas preheater is connected to the hot fluid inlet of the primary air exhaust gas preheater, and the hot fluid outlet of the primary air exhaust gas preheater is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the chimney.

[0011] Temperature sensors are evenly arranged inside the combustion chamber to monitor the temperature of the combustion chamber; a methane concentration sensor is arranged at the outlet of the mixer to monitor the methane concentration of the raw material gas entering the regenerative oxidation device.

[0012] The second technical solution adopted by the present invention is as follows: a water slurry indirect heat-supplemented type gas comprehensive utilization method: specifically as follows: The exhaust gas is divided into three paths: the first path of exhaust gas and the extracted gas are mixed in the mixer, and then enter the regenerative oxidation device for reaction. After a part of the high-temperature flue gas is recovered by the regenerator, it enters the chimney and is discharged, and the other part enters the waste heat boiler to produce steam; The second path of wind-discharged gas passes through the regulating valve V3 and the Roots blower in sequence and enters the return feeder. After being mixed with the solid particles coming down from the dust collector, it enters the furnace of the water coal slurry combustion device; The third path of wind-discharged gas is pressurized by the primary blower and the secondary blower respectively, the waste heat of the water coal slurry combustion products is recovered by the low-temperature energy-saving device, and after being preheated by the primary wind-discharged gas preheater and the secondary wind-discharged gas preheater respectively, it enters the ignition air duct and the furnace of the water coal slurry combustion device respectively as the combustion-supporting gas of the water coal slurry combustion device.

[0013] After adjusting the molar concentration of methane in the mixed gas to below 1.5%, it enters one of the regenerative heat bodies of the regenerative thermal oxidation device through the cut-off valve and is preheated to 600°C ± 25°C; it continues to absorb heat in the combustion chamber and then undergoes an oxidation reaction. After methane oxidation, CO 2 and H 2 O are generated, and a large amount of heat is produced. A part of the high-temperature flue gas generated in the combustion chamber recovers heat through the other regenerative heat body of the regenerative thermal oxidation device and then enters the chimney for exhausting. Another part of the high-temperature flue gas is extracted from the regulating valve V4 at the top of the regenerative thermal oxidation device and then enters the waste heat boiler to produce steam to provide heat for heat users. The flue gas coming out of the waste heat boiler preheats the wind-discharged gas through the low-temperature energy-saving device and then enters the chimney; The water coal slurry enters the water coal slurry combustion device after passing through the water coal slurry storage hopper. It is mixed with the wind-discharged gas coming from the secondary wind-discharged gas preheater in the furnace and then burns. The water coal slurry combustion products enter the finned heat exchange coil in the combustion chamber of the regenerative thermal oxidation device after removing solid particles through the dust collector, heating the gas in the internal space of the combustion chamber, keeping the average temperature of the combustion chamber above the temperature required for the full combustion of the gas, and increasing the temperature of the regenerative heat body close to the combustion chamber, maintaining the temperature gradient between the upper and lower parts of the regenerative heat body within the working range; the water coal slurry combustion products coming out of the finned heat exchange coil recover heat through the secondary wind-discharged gas preheater and the primary wind-discharged gas preheater respectively, and then are sent to the chimney through the induced draft fan.

[0014] The method of control using the control system is as follows: The reading of the methane concentration sensor at the outlet of the mixer is fed back to the control system. After receiving the concentration signal of this methane concentration sensor, the control system controls the opening degrees of the regulating valves V2 and V1 to make the molar concentration of methane entering the regenerative thermal oxidation device not higher than 1.5%; The control system controls the flow rate of the wind-discharged gas entering the Roots blower through the regulating valve V3 to keep the height of the solid particles in the return feeder within the set range; The control system controls the flow rate of the wind-discharged gas entering the water coal slurry combustion device as the combustion-supporting gas through the regulating valves V6 and V5 to maintain the combustion intensity of the water coal slurry and provide sufficient heat for the finned heat exchange coil; The control system controls the amount of high-temperature flue gas extracted from the top of the combustion chamber through regulating valves V6 and V5, so that the average temperature of the combustion chamber is maintained at 750°C to 950°C; When the average temperature of the combustion chamber increases to 950°C, open V3, V5, V6, and V7, and keep regulating valve V4 open to lower the average temperature of the combustion chamber; when the average temperature of the combustion chamber drops below 750°C, open regulating valves V3, V5, V6, and V7 simultaneously, and close regulating valve V4 to raise the average temperature of the combustion chamber; thus, by adjusting the opening degrees of each valve, the average temperature of the combustion chamber is maintained at 750°C to 950°C.

[0015] The beneficial effects of the present invention are as follows: When the gas extraction for gas drainage is cut off due to problems in the gas extraction pump station, the raw material gas provided to the water coal slurry partition wall type heat-supplemented gas comprehensive utilization system is only the wind-discharged gas, and the heat generated by its oxidation is no longer sufficient to maintain the self-heat balance of the regenerative oxidation device. At this time, the water coal slurry combustion device can use the heat generated by the combustion of water coal slurry and wind-discharged gas to supplement heat to the combustion chamber, so that the average temperature of the combustion chamber is maintained within the working temperature range required for methane oxidation. The high-temperature resistant tube fin heat exchange coil is a partition wall type heat exchanger. Compared with direct heat exchange, it can prevent solid particles (coal combustion, fly ash, slag, etc.) that are not completely removed by the dust collector from entering the combustion chamber, thereby avoiding the blockage of the regenerator channels due to the settlement or coking of solid particles on the surface of the regenerator channels.

[0016] The combustion-supporting gas for water coal slurry combustion uses wind-discharged gas instead of air, which can make the most of the energy of methane in the wind-discharged gas, improve the thermal efficiency of the entire gas system, and utilize more wind-discharged gas, that is, achieve zero emissions of extracted gas and wind-discharged gas.

[0017] Compared with directly mixing and supplementing heat with the high-temperature flue gas of a coal-fired furnace provided directly to the combustion chamber, it can prevent the dilution of the gas supplied for heat supplement to the gas entering the regenerative oxidation device, thereby avoiding further reduction of the methane concentration in the extremely low-concentration gas raw material, and saving heat supplement and heat supplement fuel.

[0018] Compared with heat supplement with solid fuels such as ordinary pulverized coal, water coal slurry is a deeply clean coal-based liquid fuel with stable combustion, less pollution emissions, and is much easier to feed and accurately measure to an external combustion furnace. The combustibles in it have a high combustion efficiency, a large heat supplement per unit fuel, save fuel consumption, and produce extremely low harmful gases to the atmosphere during combustion.

[0019] The above method can avoid the loss of the working temperature at each point inside the system during operation and even shutdown due to unstable flow and concentration (and even sometimes long-term interruption of supply) of the coal mine gas extraction, thereby avoiding the interruption of heat supply to heat users, reducing the risk of heat interruption, and reducing the operation cost and safety risk of the device. Description of the Drawings

[0020] Figure 1 This is a schematic structural diagram of the water coal slurry partition heat supplement type gas comprehensive utilization system of the present invention.

[0021] In the figure, 1. mixer, 2. secondary air blower, 3. primary air blower, 4. induced draft fan, 5. secondary air discharged gas preheater, 6. primary air discharged gas preheater, 7. waste heat boiler, 8. Roots blower, 9. dust collector, 10. water coal slurry combustion device, 11. ignition air duct, 12. water coal slurry storage hopper, 13. regenerative oxidation device, 14. feeder, 15. finned heat exchange coil, 16. low-temperature energy saver, 17. control system. Specific embodiments

[0022] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0023] Embodiment 1 The water coal slurry partition heat supplement type gas comprehensive utilization system of the present invention includes a mixer 1, a Roots blower 8, a feeder 14, a dust collector 9, a regenerative oxidation device 13, a secondary air discharged gas preheater 5, a primary air discharged gas preheater 6, and an induced draft fan 4 connected in sequence; the secondary air discharged gas preheater 5 is connected to the secondary air blower 2; the primary air discharged gas preheater 6 is connected to the primary air blower 3; the regenerative oxidation device 13 is connected to the waste heat boiler 7; the secondary air discharged gas preheater 5 is connected to the water coal slurry combustion device; the primary air discharged gas preheater 6 is connected to the ignition air duct 11 of the water coal slurry combustion device; it further includes a control system 17, and the control system 17 is used to control each valve body on the connecting pipeline to achieve flow regulation.

[0024] Embodiment 2 On the basis of Embodiment 1, a water coal slurry storage hopper 12 is connected to the water coal slurry combustion device 10, and the regenerative oxidation device 13 includes a combustion chamber and two groups of regenerators arranged at intervals, and a finned heat exchange coil 15 is arranged in the combustion chamber.

[0025] The outlets of the secondary air blower 2 and the primary air blower 3 are respectively connected to the two cold fluid inlets of the low-temperature energy saver 16 through regulating valves V5 and V6, and the cold fluid inlets of the secondary air discharged gas preheater 5 and the primary air discharged gas preheater 6 are respectively connected to the two cold fluid outlets of the low-temperature energy saver 16; the cold fluid outlets of the secondary air discharged gas preheater 5 and the primary air discharged gas preheater 6 are respectively connected to the furnace and the ignition air duct 11 of the water coal slurry combustion device.

[0026] The outlet of the mixer 1 is connected to the regenerator of the regenerative thermal oxidizer 13 through a cut-off valve group (S1~S4); the high-temperature flue gas outlet at the top of the regenerative thermal oxidizer 13 is connected to the heat source inlet of the waste heat boiler 7 through a regulating valve V4, the heat source outlet of the waste heat boiler 7 is connected to the hot fluid inlet of the low-temperature economizer 16, and the hot fluid outlet of the low-temperature economizer 16 is connected to the chimney.

[0027] The hot fluid inlet of the finned tube heat exchange coil 15 is connected to the outlet end of the dust collector 9, and the hot fluid outlet is connected to the hot fluid inlet of the secondary air exhaust gas preheater 5; the hot fluid outlet of the secondary air exhaust gas preheater 5 is connected to the hot fluid inlet of the primary air exhaust gas preheater 6, the hot fluid outlet of the primary air exhaust gas preheater 6 is connected to the inlet of the induced draft fan 4, and the outlet of the induced draft fan 4 is connected to the chimney.

[0028] Three temperature sensors are evenly arranged inside the combustion chamber to monitor the temperature of the combustion chamber; a methane concentration sensor is set at the outlet of the mixer 1 to monitor the methane concentration of the raw gas entering the regenerative thermal oxidizer 13.

[0029] Example 3 The water coal slurry indirect heat supply type gas comprehensive utilization system disclosed in this embodiment includes: mixer 1, secondary air blower 2, primary air blower 3, induced draft fan 4, secondary air exhaust gas preheater 5, primary air exhaust gas preheater 6, waste heat boiler 7, Roots blower 8, dust collector 9, water coal slurry combustion device 10, ignition air duct 11, water coal slurry storage hopper 12, regenerative thermal oxidizer 13 (regenerator, combustion chamber, cut-off valve, etc.), return feeder 14, high-temperature resistant finned tube heat exchange coil 15, low-temperature economizer 16, control system 17.

[0030] Among them, the exhaust gas is divided into 3 paths through pipelines and regulating valves. The first path is connected to the exhaust gas inlet of the mixer 1, the second path is connected to the Roots blower 8, and the third path is further divided into 2 paths, which are respectively connected to the inlets of the secondary air blower 2 and the primary air blower 3.

[0031] The water coal slurry combustion device 10 uses liquid fuel. Compared with solid fuels such as ordinary pulverized coal for heat supply, water coal slurry is a deeply clean coal-based liquid fuel, with stable combustion, less pollution emissions, and much easier feeding and accurate metering to an external combustion furnace. The combustibles in it have a high combustion efficiency, a large heat supply per unit fuel, save fuel consumption, and produce extremely low harmful gases to the atmosphere during combustion.

[0032] A high-temperature resistant finned tube heat exchange coil 15 is arranged inside the combustion chamber of the regenerative thermal oxidizer 13. The hot fluid inlet of the high-temperature resistant finned tube heat exchange coil 15 is connected to the outlet end of the dust collector 9, and the hot fluid outlet of the high-temperature resistant finned tube heat exchange coil 15 is connected to the hot fluid inlet of the secondary air exhaust gas preheater 5.

[0033] The high-temperature resistant tube-fin heat exchange coil 15 is a wall-type heat exchanger that indirectly supplies heat to the combustion chamber of the regenerative thermal oxidation device 13. Compared with directly mixing and supplementing heat with the high-temperature flue gas of a coal-fired furnace directly into the combustion chamber, it can prevent the dilution of the gas by the supplementary heat gas to the gas entering the regenerative thermal oxidation device, thereby avoiding further reduction of the methane concentration in the extremely low-concentration gas raw material, saving the supplementary heat quantity and supplementary heat fuel, and increasing the conversion rate of methane at extremely low concentrations. In addition, it can also prevent solid particles (coal, fly ash, slag, etc.) that are not completely removed by the dust collector 9 from entering the combustion chamber, thereby avoiding the blockage of the regenerative body channels due to the settlement or coking of solid particles on the surface of the regenerative body channels.

[0034] The setting of the secondary air exhaust gas preheater 5 and the primary air exhaust gas preheater 6 can further extract the low-temperature waste heat remaining after the heat exchange of the water slurry combustion to the combustion chamber, and make the temperature of the air exhaust gas entering the furnace of the water slurry as high as possible. The final effect is to reduce the thermal stress at the air exhaust gas inlet of the furnace, increase the service life, improve the overall thermal efficiency of the system, and reduce the exhaust gas temperature.

[0035] Example 4 Based on Example 1, the extracted gas is connected to the inlet of the mixer 1 through the regulating valve V1. The outlet of the mixer 1 is connected to the regenerative body of the regenerative thermal oxidation device 13 through a cut-off valve group. The high-temperature flue gas outlet at the top of the regenerative thermal oxidation device 13 is connected to the heat source inlet of the waste heat boiler 7 through the regulating valve V4. The heat source outlet of the waste heat boiler 7 is connected to the hot fluid inlet of the low-temperature energy saver 16, and the hot fluid outlet of the low-temperature energy saver 16 is connected to the chimney.

[0036] In this embodiment, the secondary air blower 2 and the primary air blower 3 provide power for the air exhaust gas to overcome the resistance of components such as the low-temperature energy saver 16, the secondary air exhaust gas preheater 5, the primary air exhaust gas preheater 6, the dust collector 9, and the high-temperature resistant tube-fin heat exchange coil 15. The low-temperature energy saver 16 is used to recover the waste heat of the high-temperature flue gas from the heat user, reduce the heat enthalpy of the flue gas entering the chimney as much as possible, and improve the overall thermal efficiency.

[0037] Three temperature sensors are evenly arranged inside the combustion chamber to monitor the temperature of the combustion chamber. In actual application, the average temperature of the above three temperatures is used as the operating condition control parameter of the combustion chamber, and based on this, the opening degrees of the corresponding regulating valves (V7, V3, V5, V6) and the water slurry injection amount are controlled. A methane concentration sensor is set at the outlet of the mixer to monitor the methane concentration of the raw gas entering the regenerative thermal oxidation device. This concentration mainly changes when the methane concentration and flow rate in the extracted gas change. At this time, the control system needs to control the opening degree of the regulating valve V2 to maintain the methane concentration entering the combustion chamber stable near the design value.

[0038] Example 5 The method for comprehensively utilizing gas with indirect heat supplement type for water coal slurry of the present invention is specifically implemented according to the following steps: The wind-discharged gas is divided into three paths: The first path of wind-discharged gas and the extracted gas are mixed in the mixer 1. After the concentration of the mixed gas (hereinafter, in terms of the mole fraction of methane) is adjusted to less than 1.5%, it enters the regenerative heat oxidation device 13 through the cut-off valve group and enters the regenerator of one of the oxidation beds, and is preheated to about 600 °C. In the combustion chamber, the above-mentioned gas continues to absorb heat and then undergoes an oxidation reaction. After the flue gas after the oxidation of the gas recovers heat through the regenerator of the other oxidation bed of the regenerative heat oxidation device 13, it enters the chimney and is discharged. After the methane in the gas in the combustion chamber is oxidized, it generates CO 2 and H 2 O, and generates a large amount of heat. This heat and the heat brought by the combustion products of the water coal slurry in the high-temperature finned heat exchange coil 15 together maintain the self-thermal balance of the regenerative heat oxidation device. The excess heat (controlled by the control system 17 through the regulating valve V4 according to the average temperature of the combustion chamber) is extracted through the regulating valve V4 at the top of the regenerative heat oxidation device 13 in the form of high-temperature flue gas and enters the waste heat boiler 7 to produce steam, providing heat for heat users (power generation, building heating, shaft anti-freezing, coal slime drying, absorption refrigeration, etc.). The flue gas coming out of the waste heat boiler 7 preheats the wind-discharged gas through the low-temperature economizer 16 and then enters the chimney.

[0039] The second path of wind-discharged gas sequentially passes through the regulating valve V3 and the Roots blower 8 and enters the feeder 14, mixes with the solid particles coming down from the dust collector 9, and then enters the furnace of the water coal slurry combustion device 10.

[0040] The third path of wind-discharged gas is divided into two paths. After being pressurized by the primary fan 3 and the secondary fan 2 respectively, recovering the waste heat of the combustion products of the water coal slurry through the low-temperature economizer 16, and being preheated by the primary wind-discharged gas preheater 6 and the secondary wind-discharged gas preheater 5 respectively, they enter the ignition air duct 11 and the furnace of the water coal slurry combustion device 10 respectively, serving as the combustion-supporting gas for the water coal slurry combustion device.

[0041] The combustion-supporting gas for the water coal slurry combustion uses wind-discharged gas instead of air, which can make full use of the energy of methane in the wind-discharged gas as much as possible, improve the thermal efficiency of the entire gas system, and utilize more wind-discharged gas, that is, achieve zero emissions of the extracted gas and the wind-discharged gas.

[0042] The water slurry enters the water slurry combustion device 10 after passing through the water slurry storage hopper 12, and burns in the furnace after being mixed with the air-drained gas coming from the secondary air-drained gas preheater 5. The combustion products of the water slurry enter the high-temperature resistant tube-fin heat exchange coil 15 arranged in the combustion chamber after removing solid particles through the dust collector 9, which is used to heat the gas in the internal space of the combustion chamber, so that the average temperature of the combustion chamber (taking the average value of the readings of the temperature sensors arranged in the combustion chamber, the same below) is maintained above the temperature required for the full combustion of the gas, and the temperature of the heat storage body near the combustion chamber is increased, and the temperature gradient between the upper and lower parts of the heat storage body is maintained within the working condition range. The combustion products of the water slurry coming out of the high-temperature resistant tube-fin heat exchange coil 15 recover heat through the secondary air-drained gas preheater 5 and the primary air-drained gas preheater 6 respectively, and are sent into the chimney through the induced draft fan 4.

[0043] Example 6 On the basis of Example 5, the control system 17 controls the flow rate of the air-drained gas entering the Roots blower 8 through the regulating valve V3, so that the height of the solid particles in the loop feeder 14 is maintained within a certain range.

[0044] The control system 17 controls the flow rate of the air-drained gas entering the water slurry combustion device 10 as the combustion-supporting gas through the regulating valves V6 and V5 to maintain the combustion intensity of the water slurry and provide sufficient heat for the high-temperature resistant tube-fin heat exchange coil 15.

[0045] The control system 17 controls the amount of high-temperature flue gas extracted from the top of the combustion chamber through the regulating valve V4 to maintain the average temperature of the combustion chamber at 750°C - 950°C.

[0046] After the average temperature of the combustion chamber increases to 950°C, close the regulating valves V3, V5, V6, and V7, and keep the regulating valve V4 open to appropriately reduce the average temperature of the combustion chamber. When the average temperature of the combustion chamber drops below 750°C, open the regulating valves V3, V5, V6, and V7 simultaneously, and close the regulating valve V4 to appropriately increase the average temperature of the combustion chamber. In this way, by adjusting the opening degrees of the above valves, the average temperature of the combustion chamber is maintained at about 900°C.

[0047] Using the above control method, when the extracted gas supply is interrupted due to problems with the gas extraction pump station, the raw material gas supplied to the heat source skid is only the air-drained gas, and the heat generated by its oxidation is not sufficient to maintain the self-heat balance of the regenerative oxidation device. At this time, the water slurry combustion device can use the heat generated by the combustion of the water slurry and the air-drained gas to supplement heat to the combustion chamber, so that the average temperature of the combustion chamber is maintained within the working temperature range required for methane oxidation.

[0048] The above method can avoid the working condition temperature loss of each point inside the gas heat storage oxidation device during operation due to the unstable flow rate and concentration of coal mine gas drainage (and even sometimes long-term supply interruption), until the device stops running, thereby avoiding the interruption of heat supply to heat users, reducing the heat interruption risk, and reducing the operation cost and safety risk of the device.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A water-coal slurry interlayer heat-supplementing gas comprehensive utilization system, characterized in that: The invention comprises a mixer (1), a Roots blower (8), a material return device (14), a dust collector (9), a heat storage oxidation device (13), a secondary air exhaust gas preheater (5), a primary air exhaust gas preheater (6) and an induced draft fan (4) which are connected in sequence; the secondary air exhaust gas preheater (5) is connected to the secondary air fan (2); the primary air exhaust gas preheater (6) is connected to the primary air fan (3); the heat storage oxidation device (13) is connected to a waste heat boiler (7); the secondary air exhaust gas preheater (5) is connected to a water-coal slurry combustion device; the primary air exhaust gas preheater (6) is connected to an ignition air duct (11) of the water-coal slurry combustion device; and further comprises a control system (17), the control system (17) being used to control various valve bodies on the connecting pipeline to achieve flow regulation.

2. The water-coal slurry partition type heat supplement type gas comprehensive utilization system according to claim 1 is characterized in that: The water-coal slurry combustion device (10) is connected to a water-coal slurry storage funnel (12), and the thermal storage oxidation device (13) comprises a combustion chamber and two groups of thermal storage bodies arranged at intervals, and a tube-fin heat exchange coil (15) is arranged in the combustion chamber.

3. The water-coal slurry partition-type heat-supplementing gas comprehensive utilization system according to claim 2 is characterized in that: The outlets of the secondary air fan (2) and the primary air fan (3) are connected to two cold fluid inlets of a low-temperature economizer (16) through regulating valves V5 and V6, respectively; the cold fluid inlets of the secondary air exhaust gas preheater (5) and the primary air exhaust gas preheater (6) are connected to two cold fluid outlets of the low-temperature economizer (16), respectively; and the cold fluid outlets of the secondary air exhaust gas preheater (5) and the primary air exhaust gas preheater (6) are connected to the furnace and the ignition air duct (11) of the water-coal slurry combustion device, respectively.

4. The water-coal slurry partition-type heat-supplementing gas comprehensive utilization system according to claim 3 is characterized in that: The outlet of the mixer (1) is connected to the heat storage body of the thermal storage oxidation device (13) through a cut-off valve group; the high-temperature flue gas outlet at the top of the thermal storage oxidation device (13) is connected to the heat source inlet of the waste heat boiler (7) through a regulating valve V4, the heat source outlet of the waste heat boiler (7) is connected to the hot fluid inlet of the low-temperature economizer (16), and the hot fluid outlet of the low-temperature economizer (16) is connected to the chimney.

5. The water-coal slurry partition-type heat-supplementing gas comprehensive utilization system according to claim 4 is characterized in that: The hot fluid inlet of the tube-fin heat exchange coil (15) is connected to the air outlet of the dust collector (9), and the hot fluid outlet is connected to the hot fluid inlet of the secondary air exhaust gas preheater (5); the hot fluid outlet of the secondary air exhaust gas preheater (5) is connected to the hot fluid inlet of the primary air exhaust gas preheater (6), the hot fluid outlet of the primary air exhaust gas preheater (6) is connected to the inlet of the induced draft fan (4), and the outlet of the induced draft fan (4) is connected to the chimney.

6. The water-coal slurry partition-type heat-supplementing gas comprehensive utilization system according to claim 2 is characterized in that: Three temperature sensors are evenly arranged inside the combustion chamber for monitoring the temperature of the combustion chamber; a methane concentration sensor is arranged at the outlet of the mixer (1) for monitoring the methane concentration of the raw gas entering the thermal storage oxidation device (13).

7. A method for comprehensive utilization of water-coal slurry interlayer heat-supplementing gas, characterized in that: The water-coal slurry partition-type heat-supplementing gas comprehensive utilization system according to any one of claims 1 to 6 is used, specifically as follows: The exhaust gas is divided into three routes: the exhaust gas and the extraction gas are mixed in the mixer, and then enter the thermal storage oxidation device for reaction. A part of the high-temperature flue gas is discharged into the chimney after the heat is recovered by the thermal storage body, and the other part enters the waste heat boiler to produce steam; The second exhaust gas passes through the regulating valve V3 and the Roots blower in turn and enters the return device, where it is mixed with the solid particles coming out of the dust collector and then enters the furnace of the water-coal slurry combustion device; The third exhaust gas is pressurized by the primary and secondary fans, recovers the waste heat of the water-coal slurry combustion products by the low-temperature economizer, and is preheated by the primary and secondary exhaust gas preheaters, and then enters the ignition air duct and furnace of the water-coal slurry combustion device as the combustion-supporting gas of the water-coal slurry combustion device.

8. The water-coal slurry partition type heat supplement type gas comprehensive utilization method according to claim 7, characterized in that: After the molar concentration of methane in the mixed gas is adjusted to below 1.5%, it enters one of the heat storage bodies of the thermal storage oxidation device through the cut-off valve and is preheated to 600℃±25℃; it continues to absorb heat in the combustion chamber and then undergoes oxidation reaction. After methane is oxidized, CO2 and H2O are generated, and a large amount of heat is generated. A part of the high-temperature flue gas generated in the combustion chamber is discharged into the chimney after recovering heat through another heat storage body of the thermal storage oxidation device. The other part of the high-temperature flue gas is extracted from the regulating valve V4 at the top of the thermal storage oxidation device and enters the waste heat boiler to produce steam to provide heat for heat users. The flue gas coming out of the waste heat boiler is preheated by the low-temperature economizer to exhaust gas and then enters the chimney; The water-coal slurry enters the water-coal slurry combustion device after passing through the water-coal slurry storage funnel, and is mixed with the exhaust gas from the secondary air exhaust gas preheater in the furnace and then burned. The water-coal slurry combustion products pass through the dust collector to remove solid particles and then enter the tube-fin heat exchange coil in the combustion chamber of the thermal storage oxidation device to heat the gas in the internal space of the combustion chamber so that the average temperature of the combustion chamber is maintained above the temperature required for full combustion of the gas, and the temperature of the heat storage body close to the combustion chamber is increased to maintain the temperature gradient between the upper and lower parts of the heat storage body within the operating range; the water-coal slurry combustion products coming out of the tube-fin heat exchange coil are sent into the chimney through the induced draft fan after recovering heat through the secondary air exhaust gas preheater and the primary air exhaust gas preheater.

9. The water-coal slurry partition-type heat-supplementing gas comprehensive utilization method according to claim 8, characterized in that: The specific method of controlling by using the control system is as follows: The reading of the methane concentration sensor at the outlet of the mixer (1) is fed back to the control system (17). After receiving the concentration signal of the methane concentration sensor, the control system (17) controls the opening of the regulating valves V2 and V1 so that the molar concentration of methane entering the thermal storage oxidation device is not higher than 1.5%; The control system (17) controls the flow rate of exhaust gas entering the Roots blower (8) through the regulating valve V3, so that the height of solid particles in the return device (14) is maintained within a set range; The control system (17) controls the flow rate of exhaust gas as combustion-supporting gas entering the water-coal slurry combustion device (10) through regulating valves V6 and V5, so as to maintain the combustion intensity of the water-coal slurry and provide sufficient heat for the tube-fin heat exchange coil (15); The control system (17) controls the amount of high-temperature flue gas extracted from the top of the combustion chamber through regulating valves V6 and V5, so that the average temperature of the combustion chamber is maintained at 750°C to 950°C; When the average temperature of the combustion chamber increases to 950°C, close the regulating valves V3, V5, V6, and V7, and keep the regulating valve V4 open to reduce the average temperature of the combustion chamber; when the average temperature of the combustion chamber drops below 750°C, open the regulating valves V3, V5, V6, and V7 at the same time, and close the regulating valve V4 to increase the average temperature of the combustion chamber; in this way, by adjusting the opening of each valve, the average temperature of the combustion chamber is maintained at 750°C~950°C.

Images